Rice would "express regret for the loss of innocent life," State Department spokesman Sean McCormack said during a media briefing. The department's Diplomatic Security Bureau is investigating the Sunday incident in which employees of a U.S. private military contractor Blackwater, protecting a State Department motorcade, apparently came under attack and fired back, killing a reported 11 people.

McCormack asked that conclusions not be drawn until the investigation was completed.

"There was a loss of life here. There was a firefight. We believe some innocent life was lost," McCormack said. "Nobody wants to see that. But I can't tell you who was responsible for that."

He said information from the investigation would be shared with the Iraqis "all along the way."

Meanwhile, Iraqi officials said they would withdraw Blackwater's license to operate in Iraq and start criminal proceedings against its staff. However, it was unclear whether Blackwater needed a license, since it worked for the State Department.